Technique for processing a substrate

ABSTRACT

Techniques for processing a substrate are disclosed. In one exemplary embodiment, the technique may be realized as a method for processing a substrate, the method comprising: ionizing first material and second material in an ion source chamber of an ion source, the first material being boron (B) containing material, the second material being one of phosphorous (P) containing material and arsenic (As) containing material; generating first ions containing B and second ions containing one of P and As; and extracting the first and second ions from the ion source chamber and directing the first and second ions toward the substrate.

PRIORITY

This application is a Non-Provisional Application of and claims priorityto U.S. Provisional Application Ser. No. 61/617,904, filed on Mar. 30,2011, and entitled “Techniques For Improving The Performance AndExtending The Lifetime Of An Ion Source.” The U.S. ProvisionalApplication Ser. No. 61/617,904 is incorporated in its entirety byreference.

FIELD

Present disclosure relates generally to techniques for processing asubstrate, more particularly to techniques for processing a substrateusing an ion implantation with improved ion source.

BACKGROUND

Ion implantation process is used in manufacturing of, among others,electrical and optical devices. It is used for implanting impurities ordopants to alter one or more properties of a substrate. In integratedcircuit (IC) manufacturing, the substrate may be a silicon substrate,and the process may be used alter the electrical property of thesubstrate. In solar cell manufacturing, the process may be used to alterthe optical and/or electrical property of the substrate. As theimpurities or dopants implanted into the substrate may affect theperformance of the final device, a precise and uniform implant profileis desired.

Referring to FIG. 1, there is shown a conventional indirectly heatedcathode (IHC) ion source 100 and an extraction system 112 of aconventional ion implantation system that may be used to implantimpurities or dopants. As illustrated in FIG. 1, a typical IHC ionsource 100 includes an ion source chamber 102 comprising one or moreconductive chamber walls 102 a defining an ion generation region 104.The ion source chamber 102 also includes an extraction aperture 102 b.At one side of the ion source chamber 102, there may be a cathode 106and a filament 108. Opposite to the cathode 108, there may be a repeller110.

A feed source 114 containing feed material may be coupled to the ionsource chamber 102. The feed material may contain desired implanterspecies (e.g. dopant species).

Near the extraction aperture 102 b of the ion source chamber 102, theremay be an extraction system 112. The extraction system 112 may comprisea suppression electrode 112 a positioned in front of the extractionaperture 102 b and a ground electrode 112 b. The suppression electrode112 a may be electrically coupled to a suppression power supply 116 a,whereas the ground electrode 112 b may be electrically coupled to anextraction power supply 116 a. Each of the suppression electrode 112 aand the ground electrode 112 b has an aperture aligned with theextraction aperture 102 b for extraction of the ions 20 from the ionsource chamber 102.

In operation, the feed material is introduced into the ion sourcechamber 102 from the feed source 110. The filament 108, which may becoupled to a power supply (not shown), is activated. The currentsupplied to the filament 108 may heat the filament 108 and causethermionic emission of electrons. The cathode 106, which may be coupledto another power supply (not shown), may be biased at much higherpotential. The electrons emitted from the filament 108 are thenaccelerated toward and heat the cathode 106. The heated cathode 106, inresponse, may emit electrons toward the ion generation region 104. Thechamber walls 102 a may also be biased with respect to the cathode 106so that the electrons are accelerated at a high energy into the iongeneration region 104. A source magnet (not shown) may create a magneticfield B inside the ion generation region 104 to confine the energeticelectrons, and the repeller 110 at the other end of the ion sourcechamber 102 may be biased at a same or similar potential as the cathode106 to repel the energetic electrons.

Within the ion generation region 104, energetic electrons may interactand ionize the feed material to produce plasma 10 containing, amongothers, ions of desired species 20 (e.g. desired dopants or impurities).The plasma 10 may also contain undesired ions or other fragments of thefeed materials.

The extraction power supply 116 b may provide an extraction voltage tothe ground electrode 112 b for extraction of the ion beam 20 from theion source chamber 102. The extraction voltage may be adjusted accordingto the desired energy of the ion beam 20. The suppression power supply116 a may bias the suppression electrode 112 a to inhibit movement ofelectrons within the ion beam 20

In order to manufacture devices with optimal performance, it isgenerally desirable to process the substrate with uniform ion beam withhigh beam current (i.e. high concentration or dose of desired ions).Moreover, it is desirable to implant the substrate with an ion beamhaving low beam glitch rate. A glitch is defined as a sudden degradationin the beam quality during an ion implantation operation. If theimplantation process is interrupted or affected by a glitch, thesubstrate may be negatively affected or even potentially renderedunusable. A low beam current may increase the time necessary to achieveproper implant dose in the substrate and lead to lower throughput.Meanwhile, non-uniform beam and/or high glitch rate may result innon-uniform dopant profile. Such deficiencies which are observed oftenin the ion implantation system with conventional IHC ion sources maylower the throughput and/or increase the manufacturing cost of thedevices.

The above deficiencies may be caused by, among others, films or depositsformed on the inner wall of the ion source chamber 102, extractionaperture 102 b, and the extraction electrodes 112. As noted above, theplasma 10 generated in the ion generation region 104 contains highlyreactive ions and other fragments of the feed material. Such ions andfragments may etch, sputter, or otherwise react with the materials inthe ion source chamber 100. The etched materials may then condense toform films or deposits on the ion source chamber wall 102 a, theextraction aperture 102 b, and the extraction electrodes 112. The filmsor deposits may block the extraction aperture 102 b to cause anon-uniform ion beam 20 having different doses in different regions ofthe ion beam 20. In addition, the ion beam 20 extracted may have lowbeam current. In some cases, the films or deposits may be electricallyconductive and provide ignition points in which micro/macro arcing mayoccur. Such arcing may lead to beam glitches.

One way to decrease the rate of such a defective ion beam 20 is toperiodically replace the ion source 100 with a new/clean ion source 100.However, replacement of ion source 100 requires the entire ion source100 and vacuum pumping system attached to the ion source 100 to bepowered down. Moreover, the ion source 102 must be manually replaced.Further, the process by which the ion source 100 may be cleaned is alabor intensive process. Accordingly, frequent replacement of the ionsource 100 may lower the efficiency of the ion implantation process.

With increased need for higher ion beam current for manufacturingadvanced electronic and solar cell devices, greater amount of feedmaterial is introduced and ionized in the ion source chamber 100. As aresult, higher rate of defective beam is observed during ionimplantation process. The conventional IHC ion sources may have lowperformance and low lifetime, and processing substrates in a systemcontaining the conventional IHC ion source may be less than optimal.

In view of the foregoing, it would be desirable to provide a newtechnique is needed.

SUMMARY

Techniques for processing a substrate are disclosed. In one exemplaryembodiment, the technique may be realized as a method for processing asubstrate, the method comprising: ionizing first material and secondmaterial in an ion source chamber of an ion source, the first materialbeing boron (B) containing material, the second material being one ofphosphorous (P) containing material and arsenic (As) containingmaterial; generating first ions containing B and second ions containingone of P and As; and extracting the first and second ions from the ionsource chamber and directing the first and second ions toward thesubstrate.

In accordance with other aspects of this particular exemplaryembodiment, the method may further comprise: implanting the first andsecond ions into the substrate.

In accordance with further aspects of this particular exemplaryembodiment, the method may further comprise: implanting one of the firstand second ions into the substrate without implanting the other one ofthe first and second ions into the substrate.

In accordance with other aspects of this particular exemplaryembodiment, the method may further comprise: directing the first ionsand second ions toward beam-line components; and separating the firstions and second ions in the beam-line components.

In accordance with additional aspects of this particular exemplaryembodiment, the first material may be hydride or fluoride of B, and thesecond material may be hydride or fluoride of P.

In accordance with further aspects of this particular exemplaryembodiment, the first material may be one of BF₃ and B₂F₄, and thesecond material may be one of PH₃ and PF₃.

In accordance with other aspects of this particular exemplaryembodiment, the first material may be hydride or fluoride of B, and thesecond material may be hydride or fluoride of As.

In accordance with further aspects of this particular exemplaryembodiment, the first material may be one of BF₃ and B₂F₄, and thesecond material may be one of AsH₃ and AsF₃.

In accordance with further aspects of this particular exemplaryembodiment, one of the first and second materials may be provided as asolid source in the ion source chamber and the other one of the firstand second material may be provided as a gas released into the ionsource chamber.

In accordance with additional aspects of this particular exemplaryembodiment, the solid source may be disposed on an ion source chamberwall of the ion source chamber.

In accordance with further aspects of this particular exemplaryembodiment, the ion source may further comprise a dielectric window andRF source, where the solid source may be disposed on the dielectricwindow.

In accordance with other aspects of this particular exemplaryembodiment, the first and second materials may be provided into the ionsource chamber as gases.

In accordance with further aspects of this particular exemplaryembodiment, the second material may comprises approximately 5% toapproximately 20% of total gases in the ion source chamber by volume.

In accordance with additional aspects of this particular exemplaryembodiment, the first material may comprise approximately 90% of thetotal gases in the ion source chamber by volume and the second materialmay comprise approximately 10% of the total gases in the ion sourcechamber by volume.

In another exemplary embodiment, the technique may be realized as amethod for processing a substrate, the method may comprise: providing afeed material and a diluent in an ion source chamber of an ion source,the first material being boron (B) containing material, the secondmaterial being one of phosphorous (P) containing material and arsenic(As) containing material; ionizing the feed material and a diluent inthe ion source chamber and generating first ions containing B and secondions containing one of P and As; and extracting the first and secondions from the ion source chamber.

In accordance with other aspects of this particular exemplaryembodiment, the method may further comprise implanting the first ionsinto the substrate.

In accordance with further aspects of this particular exemplaryembodiment, the feed material and the diluent are provided into the ionsource chamber as gases, and wherein diluent comprises approximately 5%to approximately 20% of total gases in the ion source chamber by volume.

In accordance with additional aspects of this particular exemplaryembodiment, the feed material is one of BF₃ and B₂F₄, and wherein thediluent is one of PH₃ and PF₃ . . . .

In accordance with further aspects of this particular exemplaryembodiment, the feed material is one of BF₃ and B₂F₄, and wherein thediluent is one of AsH₃ and AsF₃.

The present disclosure will now be described in more detail withreference to exemplary embodiments thereof as shown in the accompanyingdrawings. While the present disclosure is described below with referenceto exemplary embodiments, it should be understood that the presentdisclosure is not limited thereto. Those of ordinary skill in the arthaving access to the teachings herein will recognize additionalimplementations, modifications, and embodiments, as well as other fieldsof use, which are within the scope of the present disclosure asdescribed herein, and with respect to which the present disclosure maybe of significant utility.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to facilitate a fuller understanding of the present disclosure,reference is now made to the accompanying drawings, in which likeelements are referenced with like numerals. These drawings should not beconstrued as limiting the present disclosure, but are intended to beexemplary only.

FIG. 1 illustrates a conventional indirectly heated cathode (IHC) ionsource.

FIG. 2 illustrates an exemplary ion implantation system according to oneembodiment of the present disclosure.

FIG. 3A illustrates an exemplary ion source that may be included in theion implantation system of FIG. 2 according to one embodiment of thepresent disclosure.

FIG. 3B illustrates another exemplary ion source that may be included inthe ion implantation system of FIG. 2 according to another embodiment ofthe present disclosure.

FIG. 3C illustrates another exemplary ion source that may be included inthe ion implantation system of FIG. 2 according to another embodiment ofthe present disclosure.

FIG. 4A illustrates another exemplary ion source that may be included inthe ion implantation system of FIG. 2 according to another embodiment ofthe present disclosure.

FIG. 4B illustrates another exemplary ion source that may be included inthe ion implantation system of FIG. 2 according to another embodiment ofthe present disclosure.

FIG. 4C illustrates another exemplary ion source that may be included inthe ion implantation system of FIG. 2 according to another embodiment ofthe present disclosure.

FIG. 5 illustrates another exemplary ion source that may be included inthe ion implantation system of FIG. 2 according to another embodiment ofthe present disclosure.

FIG. 6 illustrates another exemplary ion source that may be included inthe ion implantation system of FIG. 2 according to another embodiment ofthe present disclosure.

DETAILED DESCRIPTION

Herein, several embodiments of improved techniques for processingsubstrates are disclosed. For clarity and simplicity, the presentdisclosure may focus on techniques for processing a substrate using anion implantation system with IHC ion source or RF ion source. However,those of ordinary skill in the art will recognize that the presentdisclosure may be just as applicable to system with other types of ionsources including Bernas ion source or microwave ion source.

In addition, the present disclosure focuses on the techniques forperforming p-type or n-type doping on silicon (Si) substrate. Those ofordinary skill in the art will recognize that the present disclosure isnot limited thereto,

Referring to FIG. 2, there is shown a simplified block diagram of an ionimplantation system 200 according to one embodiment of the presentdisclosure. The ion implantation system 200 may comprise an ion source100 for generating ions 30 of desired species. Downstream of the ionsource 100, there may be an extraction system 112. A substrate 232, towhich the ions 30 may be directed, may be disposed downstream of theextraction system 112. Although not required, the ion implantationsystem 200 may include one or more of beam-line components 222 which mayfocus, filter, or otherwise manipulate the ions 30 into an ion beamhaving desired properties (e.g. desired ion species, beam current, beamenergy, implant angle, etc. . . . ). Examples of the beam-linecomponents (not shown) may include a mass analyzer magnet,acceleration/deceleration stage (not shown), and a corrector magnet (notshown). The mass analyzer magnet may be configured with a particularmagnetic field such that only the ions with a desired mass-to-chargeratio are able to travel through the analyzer. As such, the massanalyzer may be able to separate the ions of desired implant species andundesired species and selective direct the ions of desired implantspecies toward the substrate 232. The corrector magnet, meanwhile, maybe energized to deflect the ion beam in accordance with the strength anddirection of the applied magnetic field to provide a beam with desiredsize and orientation.

The ion implantation system 200 may also include a material source (notshown) coupled to the ion source. As discussed in detail below, thematerial source may contain feed material and/or diluent. The feedmaterial provided into the ion source 202 from the material source maybe converted into, among others, the ions of desired implant species.

Referring to FIG. 3A-3C there are shown several exemplary ion sources302 a-302 c according to several embodiments of the present disclosure.Each of the ion sources 302 a-302 c illustrated in FIG. 3A-3C may be theion source 202 shown in FIG. 2. For clarity and simplicity, the ionsources 302 a-302 c shown in FIG. 3A-3C incorporate several componentsin the ion source 100 shown in FIG. 1 and the ion implantation system200 shown in FIG. 2. As such, the ion sources 302 a-302 c should beunderstood in relation to FIGS. 1 and 2. A detailed description of thesame components may be omitted.

As illustrated in FIG. 3A-3C, the ion sources 202 a-202 c may comprise,among others, the ion source chamber 102. The ion source chamber 102 maybe coupled to the material source 310. In the present disclosure, thematerial source 310 may comprise a feed source 312 a that provides thefeed material into the ion source chamber 102. The material source 310may also comprise a diluent source 312 b that provides diluent into theion source chamber 102. Although a single feed source 312 a and a singlediluent source 312 b are illustrated in the figure, the presentdisclosure does not preclude additional feed sources and/or additionaldiluent sources. Those of ordinary skill in the art will also recognizethat the present disclosure does not preclude a scenario where the feedmaterial and the diluent are provided in a single container and providedinto the ion source chamber 102 simultaneously.

In the present disclosure, the feed material in the feed source 312 aand diluent in the diluents source 312 b may preferably be in gaseous orvapor form. However, those of ordinary skill in the art will recognizethat some feed material as well as diluent may in solid, liquid, orother form. If in liquid or solid form, a vaporizer (not shown) may beprovided near the feed source 312 a and/or the diluents source 312 b.The vaporizer may convert solid/liquid feed material and/or diluent intogaseous or vapor form and provide the feed material and diluent into theion source chamber 102 in such a form. To control the amount of feedmaterial and the diluent introduced into the ion source chamber 102, oneor more controllers 314 a and 314 b may be optionally provided.

In one embodiment, as depicted in FIG. 3A, the feed material and thediluent may be contained separately in separate the feed source 312 aand the diluent source 312 b. The feed material and the diluent may thenbe pre-mixed in a first conduit 316 and provided into the ion sourcechamber 102 together. In another embodiment, as depicted in FIG. 3B, thefeed material from the feed source 312 a may be provided into thediluent source 312 b via the first conduit 318 a. The feed material andthe diluent may be provided into the ion source chamber 102 via thesecond conduit 318 b. Alternatively, the diluent from the diluent source312 b may be provided into the feed source 312 a. Yet in anotherembodiment, a single source containing a mixture of feed material anddiluent may be provided, and the feed material and the diluent may beprovided into the ion source chamber 102 simultaneously. In oneembodiment, as depicted in FIG. 3C, the feed material and the diluentmay also be provided into the ion source chamber 102 via separateconduits 316 a and 316 b.

In the present disclosure, various feed materials may be used. In someembodiments, the feed material may comprise two or more species, atleast one of which may be the implant species (or the first feedspecies) to be implanted into the substrate 232. Depending on thesubstrates and applications, different implant species may be used. Inthe present disclosure, the implant species may be the multivalentspecies found in Group 13-16. Herein, the multivalent species may referto as species capable of bonding with two or more univalent atoms orions (e.g. H or halogen species) found in Group 1 or 17 of the PeriodicTable to form, in a stable state, a molecule represented by XY. Thesymbol X may represent the multivalent species and the symbol Y mayrepresent the univalent species. For p-type doping of silicon (Si)substrate, the implant species in the feed material may be one or morespecies in Group 13 of the Periodic Table, such as boron (B), aluminum(Al), gallium (Ga), indium (In), and thallium (Tl). For n-type doping ofSi substrate, the implant species may be a species in Group 15 and/or 16in the Periodic Table, such as phosphorous (P), arsenic (As), antimony(Sb), bismuth (Bi), sulfur (S), selenium (Se), and tellurium (Te).

The species in other groups may also be used. For example, the speciesin Group 14 in the Periodic Table such as carbon (C), Si, germanium(Ge), antimony (Sn), and lead (Pb) may be used as the implant species inimplanting, for example, a compound semiconductor substrate, such asgallium nitride (GaN) or gallium arsenide (GaAs) substrate. Meanwhile,species C, Si, Ge, Sn, and Pb, or nitrogen (N) or oxygen (O) implantspecies may be also used to alter chemical and/or mechanical property ofother substrate or target.

In some embodiments, the feed material may contain at least one secondfeed species which may be different from the implant species. In theexample of p-type doping of Si substrate, the second feed species in thefeed material may preferably be one of fluorine (F), chlorine (Cl), andhydrogen (H) species. In other embodiments, the second feed species maybe some other species. In the present disclosure, the second feedspecies may be univalent or multivalent species.

Several examples of preferred feed material for p-type doping of Sisubstrate may include boron trifluoride (BF₃), diboron tetrafluoride(B₂F₄), borane (BH₃), diborane (B₂H₆), carborane (C₂B₁₀H₁₂), and othermaterials containing B, and one or both of H and F. In the aboveexamples, B may be the implant species, whereas H and/or F may be thesecond feed species. For n-type doping of Si substrate, the examples ofthe preferred feed material may include phosphine (PH₃), phosphoroustrifluoride (PF₃), arsine (AsH₃), arsenic trifluoride (AsF₃), arsenicpentafluoride (AsF₅), and other materials containing one or both of Pand As, and one or both of H and F. In such examples, P and/or As may bethe implant species, whereas H and/or F may be the second feed species.Other feed material containing other species may also be used for othersubstrate and/or other applications. Examples of such other feedmaterials may include silane (SiH₄), tetrafluorosilane (SiF₄), germane(GeH₄), and germanium fluoride (GeF₄). Those of ordinary skill in theart will recognize that the above list is not exhaustive. There may beother feed materials that may be used for Si substrate dopingapplications, other substrate doping applications, and otherapplications. Moreover, the feed materials listed above for Si substratedoping may also be used for non-Si substrate doping, and vice versa.

The diluent, in the present disclosure, may also include one or morevarious species. If two or more species are included in the diluent, thefirst species may be multivalent species found in Group 13-16. Inaddition, the first diluent species may be different from the first feedspecies. If included, the second diluent species may also be differentfrom the first feed species. However, the second diluent species may bethe same as or different from the second feed species. For example, ifthe second feed species is H, the second diluent species may be F, orvice versa. In another example, both the second feed species and thesecond diluent species may be H or F.

Using BF₃ as an example of the feed material, the first diluent speciesof the present disclosure may be at least one of C, N, O, Al, Si, P, S,Ga, Ge, As, Se, In, Sn, Sb, Te, Tl, Pb, and Bi. Although various speciesmay be used, examples of the preferred first diluent species may be N,C, Si, P, and As. Meanwhile, the second feed species may be H and/or F.

Several specific examples of such diluent may include methane (CH₄),carbon tetrafluoride (CF₄), ammonia (NH₃), nitrogen trifluoride (NF₃),water vapor (H₂O), oxygen difluoride (OF₂), aluminum hydride (AlH₃),aluminum fluoride (AlF₃), silane (SiH₄), silicon tetrafluoride (SiF₄),phosphine (PH₃), phosphorous trifluoride (PF₃), hydrogen sulfide (H₂ 5),digallen (Ga₂H₆), gallium fluoride (GaF₃), germane (GeH₄), germaniumtetrafluoride (GeF₄), arsine (AsH₃), arsenic trifluoride (AsF₃),hydrogen selenide (H₂Se), indium hydride (InH₃), indium fluoride (InF₃),stannane (SnH₄), tin fluoride (SnF₂), tin tetrafluoride (SnF₄), stibine(SbH₃), antimony trifluoride (SbF₃), hydrogen telluride (H₂Te),tellurium tetrafluoride (TeF₄), thallene (TlH₃), thallium fluoride(TlF), plumbane (PbH₄), lead tetrafluoride (PbF₄), bismuthane (BiH₃),and bismuth trifluoride (BiF₃). Using PH₃ as an example of the feedmaterial, examples of the first diluent species may include B, C, N, O,Al, Si, S, Ga, Ge, As, Se, In, Sn, Sb, Te, Tl, Pb, and Bi, butpreferably B, C, and Si. Meanwhile, the second diluent species may be Hand/or F. Those of ordinary skill in the art will recognize that theabove list is not exhaustive. Other hydride or fluoride of the firstdiluent species noted above may be just as applicable.

Although the examples provided above include diluent in a compound form,the present disclosure does not preclude diluent in the form of mixtureform. For example, the diluent in some embodiments may be a mixture ofN₂ gas (containing the multivalent species) and H₂ gas. The presentdisclosure also does not preclude the scenario of utilizing diluent thatcontains multiple multivalent species, such as one or more of B, C, N,O, Al, Si, P, S, Ga, Ge, As, Se, In, Sn, Sb, Te, Tl, PB, and Bi. Thoseof ordinary skill in the art will recognize that the above examples arenot exhaustive. Several of the exemplary diluent may exist in solid format room temperature. Such diluent may preferably be vaporized in the ionsource chamber 102, or vaporized and provided into the ion sourcechamber 102 in gaseous or vapor form.

Referring back to FIG. 3A-3C, the feed material and the diluent may beintroduced, concurrently or sequentially, into the ion source chamber102. The feed material and diluent may be ionized to form a plasma 22containing, among others, the ions and other fragments of the feedmaterial and the diluent. The ions 30 of the feed material and thediluent, among others, are then extracted from the ion source chamber102 by the extraction system 112 through the extraction aperture 102 b.

If the ion implantation system is capable of mass analysis (FIG. 2), thedesired implant species may be selectively directed to the substrate andimplanted. Meanwhile, species other than the implant species may beseparated from the implant species and be discarded. In the example ofp-type doping of Si substrate using BF₃ feed material and PH₃ diluent,the ions containing H, B, F, and P may be mass analyzed, and the ionscontaining B may be separated. Thereafter, the ions containing B mayselectively be directed toward the substrate 232. Meanwhile, other ionsmay preferably be prevented from reaching the substrate 232.

If the ion implantation system is incapable of mass analysis, the ionsof the implant species and other species may also be directed andimplanted into the substrate 232. In some cases, the implantation of thediluent species may cause loss of effective dose of the implant species.Using BF₃ feed material and PH₃ diluent in p-type doping of Si substratemay result in the implantation of P, an n-type dopants, along with B.Such a co-implantation p-type dopants and n-type dopants may reduce theeffect of the B implant due to compensation. As a result, loss ofeffective dose of B may be observed.

The loss, however, may be minimal if the amount of diluent provided intothe ion source chamber 102 is low (e.g. 5%-20% of the total volume ofthe feed material and the diluent). In addition, the effect may not besignificant if the diluent species chosen has much greater or muchsmaller mass/diameter. In the above example, implanting P into thesubstrate may result implant profile that is greater near the surface ofthe substrate. Meanwhile, B, with much less mass/diameter, may result inimplantation at greater depth. Moreover, the activation temperature of Pmay be lower than that of B. As such, co-implantation of P may have avery small effect on the overall property of the Si substrate. Thedetrimental effect may be reduced by additional B implant.

To further reduce the effect, it may be desirable to select the secondfeed species and the first and second diluent species that are inert tothe substrate 232. Using BF₃ feed material in p-type doping of Sisubstrate, it may be desirable to use N₂, SiH₄, SiF₄, GeH₄, or GeF₄ asdiluent. The ions of N, Si, and Ge species, even if introduced into theSi substrate, may have minimal effect on the electrical property of thesubstrate. Meanwhile, H and/or F species implanted into the substrate232 may be removed from the substrate 232 via diffusion during apost-implantation process (e.g. annealing process).

In the present disclosure, ionizing the diluent noted above with thefeed material can result in significant improvement in reducing glitchrates and extending the lifetime of the ion source 202. Without wishingto be bound to a particular theory, it is believed that the ions andother fragments of the second feed species may readily react with thecomponents in the ion source chamber 102 (e.g. the ion source chamberwall 102 a, the cathode 106, and the repeller 110) to form a byproductcapable of condensing readily. As a result, films or deposits may formon the ion source chamber wall 102 a, the extraction aperture 102 b, andthe extraction system 112. By introducing ions and other fragments ofthe diluent species that react readily with those of the second feedspecies, it is believed that the reaction between the ions and otherfragments of the second species with the components in the ion sourcechamber 102 may be suppressed. Meanwhile, the reaction between the ionsand other fragments of the diluent species and the second feed speciesmay result in formation of the byproducts in vapor phase that may beevacuated readily from the ion source chamber 102.

It is also believed that the first diluent species may react with thematerials already etched or sputtered from the components within the ionsource chamber 102 to form the byproducts in vapor phase. Removing thesebyproducts may suppress the reaction between the ions and otherfragments of the second feed species and the components in the ionsource chamber 102 and the formation of materials that can condense toform the films and deposits. With this reduction, micro/macro arcingthat leads to the beam glitches may be reduced. Moreover, the lifetimeof the ion source 202 in the ion implantation system 100 may beextended.

In several experiments, significant reduction in the glitch rate andincrease in the lifetime of the ion source have been observed. Comparedto an ion source ionizing only BF₃, ionization of BF₃ and a small amountof PH₃ (e.g. 30% or less of total volume) resulted in reduction ofglitch rate by a factor of 20 and increase in the lifetime of the ionsource by a factor of 10. A significant reduction in the glitch rate andincrease in the lifetime have also been observed after using otherdiluent described in the present disclosure. Accordingly, use ofdiluents described above may significantly improve the performance ofion source despite high beam current.

In the present disclosure, the amount of feed material and diluent thatmay be introduced into the ion source chamber 102 may vary. In oneembodiment, the amount of diluent may be about 5%-30%, preferably about10-15%, of the total volume of the feed material and the diluent.Although present disclosure does not preclude providing additionalamount of diluent, additional amount may not be preferable. Excessiveamount of the diluent may decrease the ion beam current of the implantspecies.

Referring to FIG. 4A-4C, there are shown several exemplary ion sources402 a-402 c according to several embodiments of the present disclosure.Each of the ion sources 402 a-402 c illustrated in FIG. 4A-4C may be theion source 202 shown in FIG. 2. For clarity and simplicity, the ionsources 402 a-402 c shown in FIG. 4A-4C incorporate several componentsin the ion sources 100 and 302 a-302 c shown in FIGS. 1 and 3A-3C, andthe ion implantation system 200 shown in FIG. 2. As such, the ionsources 402 a-402 c should be understood in relation to FIGS. 1, 2, and3A-3C. A detailed description of the same components will not beprovided.

As illustrated in FIG. 4A-4C, the ion sources 402 a-402 c may comprise,among others, the ion source chamber 102. The ion source chamber 102 maybe coupled to the material source 410. In the present disclosure, thematerial source 410 may comprise a feed source 412 a that provides thefeed material into the ion source chamber 102. The material source 410may also comprise a diluent source 412 b that provides diluent into theion source chamber 102. Although a single feed source 312 a and a singlediluent source 312 b are illustrated in the figure, the presentdisclosure does not preclude including additional feed sources andadditional diluent sources.

As depicted in FIG. 4A, the feed material and the diluent may becontained separately in separate feed source 412 a and the diluentsource 412 b. The feed material from the feed source 412 a may beintroduced into the ion source chamber 102 via a first conduit 416 a.Unlike the embodiments shown in FIG. 3A-3C, the diluent may be providedoutside of the ion source chamber 102 via the second conduit 416 b. Asshown in FIG. 4A, the diluent may be provided downstream of the ionsource chamber 102, between the ion source chamber 102 and theextraction system 112. For example, the diluent may be provided near theextraction aperture 102 b, near the aperture of the suppressionelectrode 112 a, or both. In another embodiment, as depicted in FIG. 4B,the diluent may be provided in the extraction system 112 via the secondconduit 416 b, preferably between the suppression electrode 112 a andthe ground electrode 112 b. In this embodiment, the diluent may beprovided near the aperture of the suppression electrode 112 a, theaperture of the ground electrode 112 b, or both. Yet in anotherembodiment, as depicted in FIG. 4C, the diluent may be provideddownstream of the extraction system 112 via the second conduit 416 b,preferably near the aperture of the ground electrode 112 b. Although notshown, those of ordinary skill in the art will recognize that thediluent may be directed toward the extraction aperture 102 b, theaperture of the suppression electrode 112 a and/or the aperture of theground electrode 112 b.

By providing the diluent outside the ion source chamber 102, formationof the ions containing the implant species, taking place within the ionsource chamber 102, may be decoupled from the glitch suppression, whichmay take place outside the ion source chamber 102 and near theextraction electrode 112. By introducing the diluent outside the ionsource chamber 102, the ions of the implant species and its densitywould not likely to be decreased significantly. As such, the current ofthe implant species may be maximized at given ion source parameters. Atthe same time, ionization of the diluent may be minimized and the flowof the diluent may suppress formation of film or deposit outside of theextraction aperture and the extraction electrode 12. Thus, the glitchingmay be reduced.

Reducing the ionization of the diluent may be advantageous in a non-massanalyzed ion implantation system. By reducing ionization of diluentspecies, implantation of the diluent species, which may otherwise reducethe effective dose of the implant species, may also be reduced.

Referring to FIG. 5, there is shown another exemplary ion source 502according to another embodiment of the present disclosure. The ionsource 502 illustrated in FIG. 5 may be the ion source 202 shown in FIG.2. For clarity and simplicity, the ion source 502 shown in FIG. 5incorporates several components in the ion sources 100, 302 a-302 c, and402 a-402 c shown in FIGS. 1, 3A-3C, and 4A-4C, and the ion implantationsystem 200 shown in FIG. 2. As such, the ion source 502 should beunderstood in relation to FIGS. 1, 2, 3A-3C, and 4A-4C. A detaileddescription of the same components will not be provided.

In the present embodiment, the ion source chamber 102 may contain asolid source 522 therein. If the ion source 502 is an IHC or Bernassource, the solid source may be provided in the interior of the ionsource chamber wall 102 a. If the ion source 502 is an RF plasma/ionsource, the solid source 522 may also be provided in the dielectricwindow facing the ion generation region 104.

The solid source 522, in the present embodiment, may contain one or bothof the feed material and the diluent. If only one of the feed materialand the diluent is contained in the solid source 522, the other one ofthe feed material and the diluent may be provided into the ion sourcechamber 102 from the material source 522.

Referring to FIG. 6, there is shown another exemplary ion source 602according to another embodiment of the present disclosure. In thisfigure, an RF plasma/ion source is shown, and this RF plasma/ion sourcemay the ion source 202 shown in FIG. 2. For clarity and simplicity, theion source 602 shown in FIG. 6 incorporates several components in theion sources 100, 302 a-302 c, 402 a-402 c, and 5 shown in FIGS. 1,3A-3C, 4A-4C, and 5, and the ion implantation system 200 shown in FIG.2. As such, the ion source 602 should be understood in relation to FIGS.1, 2, 3A-3C, 4A-4C, and 5. A detailed description of the same componentswill not be provided.

As illustrated in FIG. 6, the ion source 602 of the present embodimentmay comprise an ion source chamber 612. The ion source chamber 612 maycomprise one or more conductive chamber walls 612 a and a dielectricwindow 616 defining an ion generation region 104. The ion source chamber602 also includes an extraction aperture 612 b. The ion source chamber612 may be coupled to the material source 512. In the presentdisclosure, the material source 512 may be one of feed source and adiluent source that provides one of the feed material and diluent intothe ion source chamber 602. The feed material or the diluent from thematerial source 512 may be provided by a conduit 516. Unlike the ionsource shown in FIGS. 1, 2-5, the ion source 602 comprises RF plasmasource 614 for generating the plasma 20.

In the present embodiment, a solid source 622 may be provided on the ionsource chamber wall 612 a and/or the dielectric window 616. The solidsource 622, in the present embodiment, may contain one or both of thefeed material and the diluent. Meanwhile, the other one of the feedmaterial and the diluent may be provided into the ion source chamber 102from the material source 512.

Herein, several embodiments of improved techniques for processingsubstrates are disclosed. It should be appreciated that whileembodiments of the present disclosure are directed to introducing one ormore diluent gases for improving performance and lifetime of ion sourcesin beam-line ion implantation systems, other implementations may beprovided as well. Indeed, other various embodiments of and modificationsto the present disclosure, in addition to those described herein, willbe apparent to those of ordinary skill in the art from the foregoingdescription and accompanying drawings. Thus, such other embodiments andmodifications are intended to fall within the scope of the presentdisclosure. Further, although the present disclosure has been describedherein in the context of a particular implementation in a particularenvironment for a particular purpose, those of ordinary skill in the artwill recognize that its usefulness is not limited thereto and that thepresent disclosure may be beneficially implemented in any number ofenvironments for any number of purposes.

What is claimed is:
 1. A method for processing a substrate, the methodcomprising: ionizing first material and second material in an ion sourcechamber of an ion source, the first material being boron (B) containingmaterial, the second material being one of phosphorous (P) containingmaterial and arsenic (As) containing material; generating first ionscontaining B and second ions containing one of P and As; and extractingthe first and second ions from the ion source chamber and directing thefirst and second ions toward the substrate, wherein one of the first andsecond materials is provided as a solid source in the ion source chamberand the other one of the first and second material is provided as a gasreleased into the ion source chamber.
 2. The method according to claim1, wherein the solid source is disposed on an ion source chamber wall ofthe ion source chamber.
 3. The method according to claim 1, wherein theion source further comprises a dielectric window and RF source, whereinthe solid source is disposed on the dielectric window.